Category : Tutorials + Patches
Archive   : CCITTV42.ZIP
Filename : HAYESV42.TXT

HAYES ANNOUNCES SUPPORT FOR NEW CCITT V.42 STANDARD

ATLANTA, GA., May 2, 1988 - In continuing support of international
standards, Hayes Microcomputer Products, Inc. announced today that it
will provide products implementing the new CCITT Recommendation V.42
for point-to-point modem error-control. Hayes will offer a firmware
upgrade for present and past V-series system products to make them
compatible with the new V.42 standard.

"We have taken an active role in the evolution of the new standard
and will continue to contribute to the work of the CCITT and ANSI to
develop new standards and enhance existing ones," said Hayes President
Dennis C. Hayes. "The knowledge acquired concerning HDLC-based
protocols during the LAPB implementation for our V-series system
products will enable us to quickly respond to the V.42 needs of the
marketplace."

Establishment of the V.42 standard resolves the issue of
point-to-point modem error-control and enables the communications
industry to shift its focus to the role played in the future by public
data networks, X.25 networks and ISDN.
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V.42 AND BEYOND: THE FUTURE OF COMMUNICATIONS

After more than three years of extensive development, CCITT
Recommendation V.42 has been finalized. Following meetings just
completed in Geneva, Switzerland where it was agreed upon by Plenary
Modem Study Group XVII, V.42 now goes before the full CCITT for formal
adoption in November 1988 in Australia.

Hayes was actively involved in the process of developing CCITT
Recommendation V.42. Along with engineers from other communications
equipment manufacturers, services suppliers, PTTs and governmental
representatives, the company has participated in U.S. national
committees (US CCITT Study Group D Modem Working Party) and
internationally to share its communications expertise during the
development of this new standard.

Known as LAPM (Link Access Procedure-Modem), the primary protocol in
the V.42 standard is based on the Link Access Procedure-D Channel
(LAPD, used on the ISDN "D" [signaling] channel) international
standard. Both LAPB (used for error-control in present Hayes V-series
modems) and LAPD are based on the international standard High-level
Data Link Control (HDLC) procedures specified by the International
Standards Organization (ISO). Founding the new V.42 standard on such a
widely tested, accepted and utilized standard will provide great
benefits for its implementation. Compliance testing for LAPM will
benefit greatly from the large body of knowledge in existence
concerning HDLC-based procedures.

Basing the primary protocol for modem error-control on the LAPD
protocol adopted by ISO and CCITT supports the position Hayes and many
others favored during the development of the V.42 standard. By
developing LAPM, the CCITT has provided a firm foundation for
continuing work on advanced modem features such as data compression,
remote configuration and use of multiple virtual circuits. V.42 and
the existing X.25 standard for communications through public and
private data networks provide direction to the continuing evolution of
the dial-up data communications environment.

This new standard is important for the present, but it is even more
important for the future. V.42 provides the error-control standard for
point-to-point communication, but that is the limit of its scope. Now
that point-to-point error-control has been addressed, focus can shift
to the future and point-to-multi-point communications through the
Public Data Networks (PDN) based on X.25.

Personal computers are becoming multi-tasking systems whose
communications needs can be addressed by features such as X.25 PADs.
Hayes plans to support this need through its X.25 PAD enhancement to
the V-series system products. By combining the capabilities available
today through the PDN with the multi-tasking features of the personal
computer workstation, Hayes will provide solutions to all
communications network problems. Looking further into the future,
access to this same PDN will also be possible by way of an Integrated
Services Digital Network (ISDN) connection which uses a terminal
adapter with a built-in X.25 PAD.

In keeping with its history of implementing international standards,
Hayes plans to offer V.42 compatible data communications products in
the future which will also be compatible with the installed base of the
company's current V-series system products. Hayes will also offer a
firmware upgrade for present and past V-series system products which
will make them compatible with the new V.42 standard.

The CCITT's recommendation of an HDLC-based procedure for modem
error-control affirms the Hayes decision to base error-control in its
V-series system products on an extension of the LAPB protocol.
Knowledge concerning HDLC-based protocols will enable Hayes to quickly
respond with a V.42 upgrade for the V-series system products. The new
V.42 standard includes a number of error-control features (XID frames
and a benign recognition sequence) which Hayes has already successfully
used in its V-series system products.

CCITT Recommendation V.42, defines error-control for modems based on
existing international standards. Hayes engineers have taken an active
role in the development of the new standard, and will continue to work
as part of the CCITT and ANSI to develop new standards and enhance the
existing standards.

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